A conventional photomultiplier tube includes a photocathode provided on an end of a vacuum vessel for emitting electrons, an electron multiplying section for multiplying the emitted electrons, and an electron detecting section for detecting the multiplied electrons. A electrode-layered unit including dynodes provided with a plurality of channel regions constitutes the electron multiplying section, and a plurality of anodes arranged in association with each channel region constitutes the electron detecting section (for example, refer to patent documents 1 and 2). In such a photomultiplier tube, a connecting section protrudes from each dynode constituting the electrode-layered unit, and each connecting section is individually connected to stem pins. The electrode-layered unit is supported above the electron detecting section by the stem pins in an electrically insulated state from the electron detecting section.
Further, another known photomultiplier tube is configured in such a manner that a shaft is provided for allowing the electron multiplying section to slidably move in parallel with an axis of the photomultiplier tube during manufacture of the photomultiplier tube, and that the electron multiplying section is fixed to the shaft when the manufacture is completed (for example, refer to patent document 3).
Also, there has been provided still another photomultiplier tube in which the electrode-layered unit is supported by, in addition to stem pins connected individually to each dynode, placing the electrode-layered unit on an insulating spacer that is disposed on the periphery of the electron detecting section.
Patent document 1: Japanese Patent Application Publication No. 2000-149860 (page 3, FIG. 2)
Patent document 2: Japanese Patent Application Publication No. HEI9-288992 (page 4, FIG. 2)
Patent document 3: Japanese Patent Application Publication No. SHO62-287560 (pages 4-5, FIG. 1)